iGCSE Edexcel Biology: Use of Biological Resources

What is a 'transgenic' organism?

A transgenic organism is one that has had genetic material transferred into it from another species.

What are restriction enzymes?

The enzymes used to cut out the gene from one organism are called restriction enzymes.

What are ligase enzymes?

The enzymes used to join the gene into the DNA of another organism to plasmid are called ligase enzymes.

How do plasmids and viruses both act?

Plasmids and viruses act as vectors.

What is a vector?

A vector is used to transfer pieces of recombinant DNA into other cells

How can large amounts of insulin be produced?

Large amounts of insulin can be manufactured from genetically modified bacteria that are grown in a fermenter.

What is recombinant DNA?

The DNA from two different organisms combined that results from genetic modification is known as recombinant DNA.

Explain how a bacterium can be genetically modified.

• restriction enzyme used to cut gene / DNA / gene coding for (production of human) insulin / eq (1)

• (same) restriction enzyme to cut bacterial plasmid (1)

• (to produce) complementary pairings / sticky ends / eq (1)

• ligase enzyme used to join / insert gene / DNA into plasmid (1)

• plasmid / vector inserted into / taken up by bacterium (1)

How can a genetically modified plant be produced?

To produce a genetically modified plant, you need to introduce a new gene into a plant cell and then produce a whole plant from the single modified cell.

In what ways can genetically modified plants improve food production?

Plants have been modified to give many characteristics: to give fruit that stays ripe longer; to be resistant to weedkillers, frost, pests and diseases; to contain more vitamins or other nutrients; to produce human antibodies; to produce human antigens to act as vaccines; to tolerate drought, and so on.

Why is genetically modifying animals necessary?

Increased yield; increased resistance to disease; manufacture of human antibodies; manufacture of specific medicinal products; production of low cholesterol milk; and production of organs for transplantation.

What are the risks associated with xenotransplantation?

There may be a much greater immune rejection of xenotransplants than normal human transplants; the transplanted organ may carry pathogens; some viruses may be hidden in the DNA of the transplanted organ; and treatment of the recipient with immuno-suppressant drugs could allow pathogens to reproduce in their body.

What factors which affect plant growth need to be controlled to maximise crop yield?

light intensity, amount of carbon dioxide, temperature

How can farmers create the ideal conditions for crop growth?

glasshouses and polytunnels

Why does keeping plants enclosed increase crop yield?

it keeps them free from pests and disease

How do farmers give their plants more time to photosynthesise?

By using artificial light

How do farmers increase the temperature in glasshouses?

Glasshouses trap the heat; they can also use a heater

How do farmers increase the amount of carbon dioxide in glasshouses?

They use a paraffin heater to heat which makes carbon dioxide as a by-product

How do farmers make sure plants have enough minerals?

By adding fertiliser to the soil

What are pests?

microbes, insects and mammals that feed on crops and reduce yield

What happens when plants don't get enough minerals? What minerals are needed and what are they for?

Their growth and life processes are affected, which decreases crop yield

1. Magnesium - to produce chlorophyll. Not enough leads to yellowing of leaves

2. Nitrates - Produce amino acids for growth. Not enough leads to stunted growth

Why are pesticides used?

They kill pests, which means fewer plants are damaged or destroyed, increasing crop yield

What are pesticides?

Chemicals that kill pests

Why must pesticides be used carefully?

They are often poisionous to humans and can harm other wildlife

What is biological control?

Using other organisms to reduce the number of pests,either as predators, parasites, or by causing disease

How is using biological control better than pesticides?

they can last longer and be less harmful to wildlife

What is a concern about using biological control?

Introducing new organisms can cause problems and can become pests themselves

How do bacteria produce yoghurt?

They ferment milk to produce yogurt

What is fermentation?

When microbes break down sugars to release energy, usually by anaerobic respiration

Why is the equipment to make yoghurt sterilised?

To kill off unwanted organisms

Why is the milk pasteurised?

to kill off harmful microorganisms

What is pasteurisation?

When milk is heated to 72 degrees for 15 seconds

What microbe is used to make yoghurt?

Lactobacillus

Why is the fermenter kept at 40 degrees C?

That is the optimum temperature for bacterial growth

What do bacteria do to the lactose in the milk?

They ferment it to form lactic acid

What causes the milk to clot and solidify into yoghurt?

lactic acid

What is a fermenter?

A large container used to grow microbes in industry

What is culture medium?

The liquid that the microbes are grown in

How do companies optimise the yield of their product from a fermenter?

They keep them at optimum conditions

How is the pH monitored in a fermenter?

Using a pH probe

Why is the pH controlled in the fermenter?

To keep the pH at the optimum level for enzymes to work efficiently

How is the temperature monitored in a fermenter?

A temperature probe/recorder

Why is the temperature controlled in the fermenter?

To keep the temperature at the optimum level for enzymes to work efficiently

Why is there a water-cooled jacket around the fermenter?

So it doesn't overheat and denature enzymes

Why are there paddles to stir the fermenter?

to mix contents / evenly distribute contents / nutrients / fungi / organisms / oxygen / heat /eq (1)

What is produced when yeast respires aerobically?

It breaks down sugar to carbon dioxide and water

What does the carbon dioxide from the yeast do to the bread?

It causes it to rise

What are the ingredients in bread?

yeast, flour, water, and a bit of sugar

What causes the bread to rise?

The carbon dioxide from the respiration of the yeast

What breaks the carbohydrates in the flour into sugar?

Enzymes

What do yeast do with the sugars produced by the enzymes?

they use the sugars to produce carbon dioxide

What happens when the yeast run out of oxygen?

It begins anaerobic respiration (fermentation) and produces carbon dioxide and ethanol

What happens to the bubbles of carbon dioxide in the dough?

They expand and cause the bread to rise

What happens to the yeast when the bread is baked?

They continue to ferment until it gets too hot and they are killed. The alcohol is burned away.

Describe how to investigate what affects the rate of respiration

mix sugar, yeast and distilled water. Seal the testtube with a bung with a tube going into a sealed tube of water. Use a water bath to change the temerpature and count the number of bubbles produced in a set amount of time.

Rather than counting bubbles, what is a more accurate way to measure the rate of a reaction that produces a gas?

Use a gas syringe and measure the volume of gas produced

What is selective breeding?

mating the best organisms to get good offspring

What are some features in animals that are selected for?

maximum yield of meat or milk,good health,disease resistance, temperament,speed, fertility, good mothering skills

What are some features in plants that are selected for?

maximum yield of grain, good health, disease resistance, attractive flowers, nice spell, drought resistance

Describe the process of selective breeding

1. choose the individuals with the best characteristics, 2. breed them with each other, 3. select the best offspring and breed them together, 4. continue over several generations

What is artificial insemination?

When animals aren't mated directly, but sperm from the male is implanted into the female

What are the advantages of artificial insemination?

Safer for the female, quicker and cheaper to transport semen rather than bulls, semen can be used to impregnate multiple cows, and it canbe stored after the bull has died.

What is genetic engineering?

Taking useful genes from one organism's chromosomes into the cells of another.

What are some concerns about genetically modified crops?

1. transplanted genes may get out into the environment, creating superweeds 2. they may impact food chains or human health 3. some people are concerned that there may be problems passed on to future generations